Limitation of devices which are in commerce

As regards the technique, now a days are known trimmers on whose motorized head, in a case is clasped small head with nylon thread, in another case is desped a steel disc with fixed or leaning blades.
The use of the small head with nylon thread rends the tool suitable for the cutting and the crushing of little resistant vegetables, in particular grass, bushes and other vegetableswich can be easily cut.
The use of the disc with blades, rends the trimmer suitable for the cutting of wood or other resistant products.